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{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"wave: setframerate() accepts invalid frame rate values that round to zero","articleBody":"# Bug report\n\n### Bug description:\n\nThe `wave.Wave_write.setframerate()` method currently validates the frame rate before rounding it to an integer. This allows invalid values like `0.5` to pass validation (since `0.5 > 0`), but then get rounded to `0`, resulting in an invalid frame rate being stored internally.\n\nThis causes a confusing user experience: `setframerate(0.5)` succeeds silently, but later operations fail with the misleading error message `\"sampling rate not specified\"` instead of raising a clear error at the point where the bad value was provided.\n\nIt was found in the PR review for #132448 by @picnixz but as that PR is not merged and might not get merged, I think it makes sense to raise this separately.\n\n## current behavior\n\n```python\nimport wave\nimport io\n\nf = wave.open(io.BytesIO(), 'wb')\nf.setnchannels(1)\nf.setsampwidth(2)\nf.setframerate(0.5)  # No error raised!\nprint(f.getframerate())  # Outputs: 0\n\n# Later, when trying to write:\nf.writeframes(b'\\x00\\x00\\x00\\x00')\n# wave.Error: sampling rate not specified  \u003c-- Confusing delayed error!\n```\n\nThe value `0.5` passes the `framerate \u003c= 0` check because `0.5 > 0`, but `int(round(0.5))` evaluates to `0`. This creates a confusing user experience where:\n1. `setframerate(0.5)` succeeds with no error\n2. The error only appears later during `writeframes()` \n3. The error message is misleading: \"not specified\" when a value **was** specified\n\n## expected behavior\n\n`setframerate(0.5)` should immediately raise `wave.Error('bad frame rate')` because the rounded value is `0`, which is invalid. This provides clear, immediate feedback at the point where the error occurs, rather than a confusing delayed error.\n\nI understand that wave files with such low framerates are not usable, but the bug fix is trivial so we should just as well fix this.\n\n### CPython versions tested on:\n\nCPython main branch\n\n### Operating systems tested on:\n\nLinux\n\n\u003c!-- gh-linked-prs -->\n### Linked PRs\n* gh-144976\n\u003c!-- /gh-linked-prs -->\n","author":{"url":"https://github.com/mbeijen","@type":"Person","name":"mbeijen"},"datePublished":"2026-02-18T20:27:49Z","url":"https://github.com/python/cpython/issues/144975"}